Current endoscopic operation especially with soft tissue is performed using a tube system containing two or more inbuilt channels. Through these inbuilt channels, the rod lens camera system, the light source and the endoscopic working instruments are introduced into the site for carrying out the operation. Though it has been used for years, persistent shortcomings are found to be significantly affecting efficiency of the operation conducted through this system. For example, miniaturization of the working instruments in such system has taken toll on its efficiency in operation in contrast to microsurgery especially in removing tumors and the similar lesion. Furthermore, parallel introduction of the working instrument, camera and light source in a single tube has limited functionality of each component to act independently for operation. Moreover, movement of the entire tube in delicate soft tissue like brain tissue may prone to inflict additional damages to the patients as well. Therefore, a new instrument with features obviating the above mentioned disadvantages is needed.
International Patent publication no. 2006050047 discloses an apparatus for accessing brain tissue. The disclosed apparatus mainly comprises an obturator and cannula assembly including a dilating obturator having an a traumatic dilating tip, an optical window and a shaft portion, while the cannula disposed around the dilating obturator shaft portion. The invention is claimed to be less invasive compared to the conventional apparatus yet an additional stylet with navigation array for image guidance is required to be initially inserted as a pilot before the actual cannula is deployed.
A multiple tract cannula system is provided in United State patent with publication no. 2008004630. The disclosed system is a tubular extension having multiple attachment members attached and protruded out from the exterior surface of the tubular extension in different direction. The attachment member is used to contact and deliver therapeutic agent to the brain tissue.
Zinkel has filed a patent with publication no. 2004024291 claiming an apparatus for spinal surgery which capable of minimizing tissue trauma in the surgery. This invention is not suitable to be used for soft delicate tissue like brain. As the deployment of this invention do provide a large channel for operation, however, the tunnel itself is not enclosed to avoid injuries inflicted onto the delicate brain tissue caused by the inserted working instruments. Furthermore, it lacks of other feature such as means to hold the light source or camera that can greatly improve convenience in conducting the surgery.
Another U.S. patent application Ser. No. 5,320,611 discloses an expandable cannula for surgery having longitudinal wires circumferentially surrounded by an elastic sheath. The longitudinal wires of the disclosed invention are expandable radially outwardly upon insertion of a dilator and retract its original size upon removal of the dilator caused by the contract of the elastic sheath.